How we cite our quotes: (Chapter. Paragraph)
Quote #1
At once, with contemptuous perversity, Mr. Vladimir changed the language, and began to speak idiomatic English without the slightest trace of a foreign accent. (2.30)
Mr. Vladimir is something of a cultural chameleon. His name suggests that he's Russian, but then again, this might just be a code name like "Yellow Dart" or "Swamp Thing" (that's the one no one wants). Also, his ability to suddenly switch between languages without a trace of an accent suggests that he's even more familiar with the world of deception than Verloc. This gives Vladimir a very intimidating vibe, and it's part of what makes Verloc afraid of him. This ability to shift languages also shows that Mr. Vladimir has no principles, no core moral beliefs that he's trying to protect. He's a total cynic, and is willing to do anything he can to crush the people who actually do have moral ideals. Pardon our (flawless, idiomatic) French, but the dude's a bit of a meanie.
Quote #2
"As I've had occasion to observe before, a fatal infatuation for an unworthy—[…] Ah yes. The unlucky attachment—of your youth. She got hold of the money, and then sold you to the police—eh?" (2.43, 2.45)
Mr. Vladimir totally grills Verloc on how he (Verloc) got caught by the French police in his younger years. Verloc tries to explain that he went all goo-gah over a femme fatale who sold him out to the police, but Mr. Vladimir doesn't care. Femme fatales are a dime a dozen in the spy game. This might not seem all that important, but it's significant for showing that Verloc himself has been the victim of deception in the past. While it might not justify his lying to Winnie, it definitely makes the guy a lot more human.
Quote #3
His voice, famous for years at open-air meetings and at workmen's assemblies in large halls, had contributed, he said, to his reputation of a good and trustworthy comrade. (2.61)
When he finally has something resembling an upper hand with Mr. Vladimir, Verloc decides to show off his booming voice, which has made him trustworthy as an undercover agent because its allowed him to speak at open-air meetings and to look like a good leader. That said, this is a pretty superficial way to gain peoples trust, and the book might be critical of just how easy it is to fool people. In any case, Mr. Vladimir isn't impressed, and doesn't care about how well Verloc can deceive people. What he cares about is getting the police to stop worrying about people's rights and to start taking down left-wing thinkers whether they've committed crimes or not.